There are two colons in the following lines a radio personality is speaking. How does the speaker get his listeners to feel the existence of colons? Maybe intonation? or a shorter pause?

(On the radio)

”Listeners, that brings us to the end of another Potterwatch. We don’t know when it will be possible to broadcast again, but you can be sure we shall be back. Keep twiddling those dials: The next password will be ‘Mad-Eye.’ Keep each other safe: Keep faith. Good night.” (Harry Potter and the Deathly Hallows (7) [US Version p.444])